Systems and methods for improved communication efficiency in high efficiency wireless networks

ABSTRACT

Methods and apparatus for adjusting transmission power in wireless networks are provided. One aspect of the disclosure provides a method of wireless communication over a wireless communication medium. The method includes determining a level of interference for a data transmission from a transmitting device to an intended receiving device. The method further includes setting a transmission power level for transmitting a message based on the interference level, the message comprising one of a request-to-send (RTS) packet and a clear-to-send (CTS) packet. The method further includes transmitting the message at the set transmission power level.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(e) to U.S.Provisional Patent Application No. 61/897,135 entitled “SYSTEMS ANDMETHODS FOR IMPROVED COMMUNICATION EFFICIENCY IN HIGH EFFICIENCYWIRELESS NETWORKS” filed on Oct. 29, 2013 the disclosure of which ishereby incorporated by reference in its entirety. This applicationfurther claims priority under 35 U.S.C. §119(e) to U.S. ProvisionalPatent Application No. 61/924,156, entitled “SYSTEMS AND METHODS FORIMPROVED COMMUNICATION EFFICIENCY IN HIGH EFFICIENCY WIRELESS NETWORKS,”filed Jan. 6, 2014, assigned to the assignee hereof and incorporatedherein by reference in its entirety. This application further claimspriority under 35 U.S.C. §119(e) to U.S. Provisional Patent ApplicationNo. 61/928,845, entitled “SYSTEMS AND METHODS FOR IMPROVED COMMUNICATIONEFFICIENCY IN HIGH EFFICIENCY WIRELESS NETWORKS,” filed Jan. 17, 2014,assigned to the assignee hereof and incorporated herein by reference inits entirety.

FIELD

Certain aspects of the present disclosure generally relate to wirelesscommunications, and more particularly, to methods and apparatus foradjusting transmission power in wireless networks.

BACKGROUND

In many telecommunication systems, communications networks are used toexchange messages among several interacting spatially-separated devices.Networks can be classified according to geographic scope, which couldbe, for example, a metropolitan area, a local area, or a personal area.Such networks can be designated respectively as a wide area network(WAN), metropolitan area network (MAN), local area network (LAN), orpersonal area network (PAN). Networks also differ according to theswitching/routing technique used to interconnect the various networknodes and devices (e.g., circuit switching vs. packet switching), thetype of physical media employed for transmission (e.g., wired vs.wireless), and the set of communication protocols used (e.g., Internetprotocol suite, SONET (Synchronous Optical Networking), Ethernet, etc.).

Wireless networks are often preferred when the network elements aremobile and thus have dynamic connectivity needs, or if the networkarchitecture is formed in an ad hoc, rather than fixed, topology.Wireless networks employ intangible physical media in an unguidedpropagation mode using electromagnetic waves in the radio, microwave,infra-red, optical, etc. frequency bands. Wireless networksadvantageously facilitate user mobility and rapid field deployment whencompared to fixed wired networks.

The devices in a wireless network can transmit/receive informationbetween each other. Device transmissions can interfere with each other,and certain transmissions can selectively block other transmissions.Where many devices share a communication network, congestion andinefficient link usage can result. As such, systems, methods, andnon-transitory computer-readable media are needed for improvingcommunication efficiency in high efficiency wireless networks.

SUMMARY

Various implementations of systems, methods and devices within the scopeof the appended claims each have several aspects, no single one of whichis solely responsible for the desirable attributes described herein.Without limiting the scope of the appended claims, some prominentfeatures are described herein.

Details of one or more implementations of the subject matter describedin this specification are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages will becomeapparent from the description, the drawings, and the claims. Note thatthe relative dimensions of the following figures may not be drawn toscale.

One aspect of the disclosure provides a method of wireless communicationover a wireless communication medium. The method includes determining alevel of interference for a data transmission from a transmitting deviceto an intended receiving device. The method further includes setting atransmission power level for transmitting a message based on theinterference level, the message comprising one of a request-to-send(RTS) packet and a clear-to-send (CTS) packet. The method furtherincludes transmitting the message at the set transmission power level.

In various embodiments, the message reserving the wireless medium caninclude one of a request-to-send (RTS) packet and a clear-to-send (CTS)packet. In various embodiments, the transmission metric can include apacket error rate (PER).

In various embodiments, the method can further include identifying oneor more potentially interfering devices. The method can further includeordering the potentially interfering devices based on an estimatedtransmit power to reach each potentially interfering device. The methodcan further include setting the transmission power for the messagereserving the wireless medium further based on the ordering.

In various embodiments, setting the transmission power of the messagereserving the wireless medium can include selecting a lowest estimatedtransmit power in the ordering, and selecting a next highest estimatedtransmit power in the ordering when the interference metric crosses athreshold value.

In various embodiments, identifying the one or more potentiallyinterfering devices can include scanning for neighboring basic servicesets (BSSs), transmitting a querying message to an intended recipient ofthe data transmission, and identifying devices included in a neighboringBSS, but not visible to or detected by the intended recipient of thedata transmission, as potentially interfering devices.

In various embodiments, the estimated transmit power is based on atransmit power control (TPC) information element (IE) included in abeacon. In various embodiments, potentially interfering devices comprisedevices producing acknowledgement (ACK) interference.

Another aspect provides an apparatus configured to perform wirelesscommunication over a wireless communication medium. The apparatusincludes a processor configured to determine a level of interference fora data transmission to an intended receiving device n. The processor isfurther configured to set a transmission power, for a message based onthe interference level. The apparatus further includes a transmitterconfigured to transmit the message at the set transmission power level.

In various embodiments, the message reserving the wireless medium caninclude one of a request-to-send (RTS) packet and a clear-to-send (CTS)packet. In various embodiments, the transmission metric can include apacket error rate (PER).

In various embodiments, the processor can be further configured toidentify one or more potentially interfering devices. The processor canbe further configured to order the potentially interfering devices basedon an estimated transmit power to reach each potentially interferingdevice. The processor can be further configured to set the transmissionpower for the message reserving the wireless medium further based on theordering.

In various embodiments, the processor can be further configured toselect a lowest estimated transmit power in the ordering. The processorcan be further configured to select a next highest estimated transmitpower in the ordering when the interference metric crosses a thresholdvalue.

In various embodiments, the apparatus can further include a receiverconfigured to scan for neighboring basic service sets (BSSs). Thetransmitter can be further configured to transmit a querying message toan intended recipient of the data transmission. The processor can befurther configured to identify devices included in a neighboring BSS,but not visible to or detected by the intended recipient of the datatransmission, as potentially interfering devices.

In various embodiments, the estimated transmit power is based on atransmit power control (TPC) information element (IE) included in abeacon. In various embodiments, potentially interfering devices comprisedevices producing acknowledgement (ACK) interference.

Another aspect provides an apparatus for wireless communication over awireless communication medium. The apparatus includes means fordetermining a level of interference for a data transmission to anintended receiving device. The apparatus further includes means forsetting a transmission power level for transmitting a message reservingthe wireless medium, based on the interference level, the messagecomprising one of a request-to-send (RTS) packet and a clear-to-send(CTS) packet. The apparatus further includes means for transmitting themessage at the set transmission power level.

In various embodiments, the message reserving the wireless medium caninclude one of a request-to-send (RTS) packet and a clear-to-send (CTS)packet. In various embodiments, the transmission metric can include apacket error rate (PER).

In various embodiments, the apparatus can further include means foridentifying one or more potentially interfering devices. The apparatuscan further include means for ordering the potentially interferingdevices based on an estimated transmit power to reach each potentiallyinterfering device. The apparatus can further include means for settingthe transmission power for the message reserving the wireless mediumfurther based on the ordering.

In various embodiments, means for setting the transmission power of themessage reserving the wireless medium can include means for selecting alowest estimated transmit power in the ordering and means for selectinga next highest estimated transmit power in the ordering when theinterference metric crosses a threshold value.

In various embodiments, means for identifying the one or morepotentially interfering devices can include means for scanning forneighboring basic service sets (BSSs), means for transmitting a queryingmessage to an intended recipient of the data transmission, and means foridentifying devices included in a neighboring BSS, but not visible to ordetected by the intended recipient of the data transmission, aspotentially interfering devices.

In various embodiments, the estimated transmit power is based on atransmit power control (TPC) information element (IE) included in abeacon. In various embodiments, potentially interfering devices comprisedevices producing acknowledgement (ACK) interference.

Another aspect provides a non-transitory computer-readable medium. Themedium includes code that, when executed, causes an apparatus todetermine a level of interference for a data transmission from atransmitting device to an intended receiving device. The medium furtherincludes code that, when executed, causes the apparatus to set atransmission power level for transmitting a message reserving thewireless medium, based on the interference level, the message comprisingone of a request-to-send (RTS) packet and a clear-to-send (CTS) packet.The medium further includes code that, when executed, causes theapparatus to transmit the message the message at the set transmissionpower level.

In various embodiments, the message reserving the wireless medium caninclude one of a request-to-send (RTS) packet and a clear-to-send (CTS)packet. In various embodiments, the transmission metric can include apacket error rate (PER).

In various embodiments, the medium can further include code that, whenexecuted, causes the apparatus to identify one or more potentiallyinterfering devices. The medium can further include code that, whenexecuted, causes the apparatus to order the potentially interferingdevices based on an estimated transmit power to reach each potentiallyinterfering device. The medium can further include code that, whenexecuted, causes the apparatus to set the transmission power for themessage reserving the wireless medium further based on the ordering.

In various embodiments, setting the transmission power of the messagereserving the wireless medium can include selecting a lowest estimatedtransmit power in the ordering and selecting a next highest estimatedtransmit power in the ordering when the interference metric crosses athreshold value.

In various embodiments, identifying the one or more potentiallyinterfering devices can include scanning for neighboring basic servicesets (BSSs), transmitting a querying message to an intended recipient ofthe data transmission, and identifying devices included in a neighboringBSS, but not visible to or detected by the intended recipient of thedata transmission, as potentially interfering devices.

In various embodiments, the estimated transmit power is based on atransmit power control (TPC) information element (IE) included in abeacon. In various embodiments, potentially interfering devices comprisedevices producing acknowledgement (ACK) interference.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a wireless communication system inwhich aspects of the present disclosure can be employed.

FIG. 2 illustrates various components that can be utilized in a wirelessdevice that can be employed within the wireless communication system ofFIG. 1.

FIG. 3 is a diagram of an exemplary wireless communication system.

FIG. 4 is a diagram of an exemplary RTS/CTS exchange.

FIG. 5 is a diagram of an exemplary RTS/CTS exchange.

FIG. 6 is a time sequence diagram of the RTS/CTS exchange

FIG. 7 is a diagram of an exemplary RTS/CTS exchange in a wirelesscommunication system.

FIG. 8 shows a flowchart for an exemplary method of wirelesscommunication that can be employed within the wireless communicationsystem of FIG. 1.

FIG. 9 shows a flowchart for an exemplary method of wirelesscommunication that can be employed within the wireless communicationsystem of FIG. 1.

DETAILED DESCRIPTION

Various aspects of the novel systems, apparatuses, and methods aredescribed more fully hereinafter with reference to the accompanyingdrawings. The teachings disclosure can, however, be embodied in manydifferent forms and should not be construed as limited to any specificstructure or function presented throughout this disclosure. Rather,these aspects are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the disclosure to thoseskilled in the art. Based on the teachings herein one skilled in the artshould appreciate that the scope of the disclosure is intended to coverany aspect of the novel systems, apparatuses, and methods disclosedherein, whether implemented independently of or combined with any otheraspect of the invention. For example, an apparatus can be implemented ora method can be practiced using any number of the aspects set forthherein. In addition, the scope of the invention is intended to coversuch an apparatus or method which is practiced using other structure,functionality, or structure and functionality in addition to or otherthan the various aspects of the invention set forth herein. It should beunderstood that any aspect disclosed herein can be embodied by one ormore elements of a claim.

Although particular aspects are described herein, many variations andpermutations of these aspects fall within the scope of the disclosure.Although some benefits and advantages of the preferred aspects arementioned, the scope of the disclosure is not intended to be limited toparticular benefits, uses, or objectives. Rather, aspects of thedisclosure are intended to be broadly applicable to different wirelesstechnologies, system configurations, networks, and transmissionprotocols, some of which are illustrated by way of example in thefigures and in the following description of the preferred aspects. Thedetailed description and drawings are merely illustrative of thedisclosure rather than limiting, the scope of the disclosure beingdefined by the appended claims and equivalents thereof.

Wireless network technologies can include various types of wirelesslocal area networks (WLANs). A WLAN can be used to interconnect nearbydevices together, employing widely used networking protocols. Thevarious aspects described herein can apply to any communicationstandard, such as Wi-Fi or, more generally, any member of the IEEE802.11 family of wireless protocols.

In some aspects, wireless signals can be transmitted according to ahigh-efficiency 802.11 protocol using orthogonal frequency-divisionmultiplexing (OFDM), direct-sequence spread spectrum (DSSS)communications, a combination of OFDM and DSSS communications, or otherschemes. Implementations of the high-efficiency 802.11 protocol can beused for Internet access, sensors, metering, smart grid networks, orother wireless applications. Advantageously, aspects of certain devicesimplementing this particular wireless protocol can consume less powerthan devices implementing other wireless protocols, can be used totransmit wireless signals across short distances, and/or can be able totransmit signals less likely to be blocked by objects, such as humans.

In some implementations, a WLAN includes various devices which are thecomponents that access the wireless network. For example, there can betwo types of devices: access points (“APs”) and clients (also referredto as stations, or “STAs”). In general, an AP serves as a hub or basestation for the WLAN and an STA serves as a user of the WLAN. Forexample, a STA can be a laptop computer, a personal digital assistant(PDA), a mobile phone, etc. In an example, an STA connects to an AP viaa Wi-Fi (e.g., IEEE 802.11 protocol such as 802.11ah) compliant wirelesslink to obtain general connectivity to the Internet or to other widearea networks. In some implementations an STA can also be used as an AP.

The techniques described herein can be used for various broadbandwireless communication systems, including communication systems that arebased on an orthogonal multiplexing scheme. Examples of suchcommunication systems include Spatial Division Multiple Access (SDMA),Time Division Multiple Access (TDMA), Orthogonal Frequency DivisionMultiple Access (OFDMA) systems, Single-Carrier Frequency DivisionMultiple Access (SC-FDMA) systems, and so forth. An SDMA system canutilize sufficiently different directions to concurrently transmit databelonging to multiple user terminals. A TDMA system can allow multipleuser terminals to share the same frequency channel by dividing thetransmission signal into different time slots, each time slot beingassigned to different user terminal. A TDMA system can implement GSM orsome other standards known in the art. An OFDMA system utilizesorthogonal frequency division multiplexing (OFDM), which is a modulationtechnique that partitions the overall system bandwidth into multipleorthogonal sub-carriers. These sub-carriers can also be called tones,bins, etc. With OFDM, each sub-carrier can be independently modulatedwith data. An OFDM system can implement IEEE 802.11 or some otherstandards known in the art. An SC-FDMA system can utilize interleavedFDMA (IFDMA) to transmit on sub-carriers that are distributed across thesystem bandwidth, localized FDMA (LFDMA) to transmit on a block ofadjacent sub-carriers, or enhanced FDMA (EFDMA) to transmit on multipleblocks of adjacent sub-carriers. In general, modulation symbols are sentin the frequency domain with OFDM and in the time domain with SC-FDMA. ASC-FDMA system can implement 3GPP-LTE (3rd Generation PartnershipProject Long Term Evolution) or other standards.

The teachings herein can be incorporated into (e.g., implemented withinor performed by) a variety of wired or wireless apparatuses (e.g.,nodes). In some aspects, a wireless node implemented in accordance withthe teachings herein can comprise an access point or an access terminal.

An access point (“AP”) can comprise, be implemented as, or known as aNodeB, Radio Network Controller (“RNC”), eNodeB, Base Station Controller(“BSC”), Base Transceiver Station (“BTS”), Base Station (“BS”),Transceiver Function (“TF”), Radio Router, Radio Transceiver, BasicService Set (“BSS”), Extended Service Set (“ES S”), Radio Base Station(“RBS”), or some other terminology.

A station (“STA”) can also comprise, be implemented as, or known as auser terminal, an access terminal (“AT”), a subscriber station, asubscriber unit, a mobile station, a remote station, a remote terminal,a user agent, a user device, user equipment, or some other terminology.In some implementations an access terminal can comprise a cellulartelephone, a cordless telephone, a Session Initiation Protocol (“SIP”)phone, a wireless local loop (“WLL”) station, a personal digitalassistant (“PDA”), a handheld device having wireless connectioncapability, or some other suitable processing device connected to awireless modem. Accordingly, one or more aspects taught herein can beincorporated into a phone (e.g., a cellular phone or smartphone), acomputer (e.g., a laptop), a portable communication device, a headset, aportable computing device (e.g., a personal data assistant), anentertainment device (e.g., a music or video device, or a satelliteradio), a gaming device or system, a global positioning system device,or any other suitable device that is configured to communicate via awireless medium.

As discussed above, certain of the devices described herein canimplement the 802.11ah standard, for example. Such devices, whether usedas an STA or AP or other device, can be used for smart metering or in asmart grid network. Such devices can provide sensor applications or beused in home automation. The devices can instead or in addition be usedin a healthcare context, for example for personal healthcare. They canalso be used for surveillance, to enable extended-range Internetconnectivity (e.g., for use with hotspots), or to implementmachine-to-machine communications.

FIG. 1 illustrates an example of a wireless communication system 100 inwhich aspects of the present disclosure can be employed. The wirelesscommunication system 100 can operate pursuant to a wireless standard,for example at least one of the 802.11ah, 802.11ac, 802.11n, 802.11g and802.11b standards. The wireless communication system 100 can include anAP 104, which communicates with STAs 106.

A variety of processes and methods can be used for transmissions in thewireless communication system 100 between the AP 104 and the STAs 106.For example, signals can be transmitted and received between the AP 104and the STAs 106 in accordance with OFDM/OFDMA techniques. If this isthe case, the wireless communication system 100 can be referred to as anOFDM/OFDMA system. Alternatively, signals can be transmitted andreceived between the AP 104 and the STAs 106 in accordance with CDMAtechniques. If this is the case, the wireless communication system 100can be referred to as a CDMA system.

A communication link that facilitates transmission from the AP 104 toone or more of the STAs 106 can be referred to as a downlink (DL) 108,and a communication link that facilitates transmission from one or moreof the STAs 106 to the AP 104 can be referred to as an uplink (UL) 110.Alternatively, a downlink 108 can be referred to as a forward link or aforward channel, and an uplink 110 can be referred to as a reverse linkor a reverse channel.

The AP 104 can provide wireless communication coverage in a basicservice area (BSA) 102. The AP 104 along with the STAs 106 associatedwith the AP 104 and that use the AP 104 for communication can bereferred to as a basic service set (BSS). It should be noted that thewireless communication system 100 may not have a central AP 104, butrather can function as a peer-to-peer network between the STAs 106.Accordingly, the functions of the AP 104 described herein canalternatively be performed by one or more of the STAs 106.

FIG. 2 illustrates various components that can be utilized in a wirelessdevice 202 that can be employed within the wireless communication system100. The wireless device 202 is an example of a device that can beconfigured to implement the various methods described herein. Forexample, the wireless device 202 can comprise the AP 104 or one of theSTAs 106.

The wireless device 202 can include a processor 204 which controlsoperation of the wireless device 202. The processor 204 can also bereferred to as a central processing unit (CPU). Memory 206, which caninclude both read-only memory (ROM) and random access memory (RAM),provides instructions and data to the processor 204. A portion of thememory 206 can also include non-volatile random access memory (NVRAM).The processor 204 typically performs logical and arithmetic operationsbased on program instructions stored within the memory 206. Theinstructions in the memory 206 can be executable to implement themethods described herein.

The processor 204 can comprise or be a component of a processing systemimplemented with one or more processors. The one or more processors canbe implemented with any combination of general-purpose microprocessors,microcontrollers, digital signal processors (DSPs), field programmablegate array (FPGAs), programmable logic devices (PLDs), controllers,state machines, gated logic, discrete hardware components, dedicatedhardware finite state machines, or any other suitable entities that canperform calculations or other manipulations of information.

The processing system can also include machine-readable media forstoring software. Software shall be construed broadly to mean any typeof instructions, whether referred to as software, firmware, middleware,microcode, hardware description language, or otherwise. Instructions caninclude code (e.g., in source code format, binary code format,executable code format, or any other suitable format of code). Theinstructions, when executed by the one or more processors, cause theprocessing system to perform the various functions described herein.

The wireless device 202 can also include a housing 208 that can includea transmitter 210 and a receiver 212 to allow transmission and receptionof data between the wireless device 202 and a remote location. Thetransmitter 210 and receiver 212 can be combined into a transceiver 214.An antenna 216 can be attached to the housing 208 and electricallycoupled to the transceiver 214. The wireless device 202 can also include(not shown) multiple transmitters, multiple receivers, multipletransceivers, and/or multiple antennas, which can be utilized duringMIMO communications, for example.

The wireless device 202 can also include a signal detector 218 that canbe used in an effort to detect and quantify the level of signalsreceived by the transceiver 214. The signal detector 218 can detect suchsignals as total energy, energy per subcarrier per symbol, powerspectral density and other signals. The wireless device 202 can alsoinclude a digital signal processor (DSP) 220 for use in processingsignals. The DSP 220 can be configured to generate a data unit fortransmission. In some aspects, the data unit can comprise a physicallayer data unit (PPDU). In some aspects, the PPDU is referred to as apacket.

The wireless device 202 can further comprise a user interface 222 insome aspects. The user interface 222 can comprise a keypad, amicrophone, a speaker, and/or a display. The user interface 222 caninclude any element or component that conveys information to a user ofthe wireless device 202 and/or receives input from the user.

The various components of the wireless device 202 can be coupledtogether by a bus system 226. The bus system 226 can include a data bus,for example, as well as a power bus, a control signal bus, and a statussignal bus in addition to the data bus. Those of skill in the art willappreciate the components of the wireless device 202 can be coupledtogether or accept or provide inputs to each other using some othermechanism.

Although a number of separate components are illustrated in FIG. 2,those of skill in the art will recognize that one or more of thecomponents can be combined or commonly implemented. For example, theprocessor 204 can be used to implement not only the functionalitydescribed above with respect to the processor 204, but also to implementthe functionality described above with respect to the signal detector218 and/or the DSP 220. Further, each of the components illustrated inFIG. 2 can be implemented using a plurality of separate elements.

As discussed above, the wireless device 202 can comprise an AP 104 or anSTA 106, and can be used to transmit and/or receive communications. Thecommunications exchanged between devices in a wireless network caninclude data units which can comprise packets or frames. In someaspects, the data units can include data frames, control frames, and/ormanagement frames. Data frames can be used for transmitting data from anAP and/or a STA to other APs and/or STAs. Control frames can be usedtogether with data frames for performing various operations and forreliably delivering data (e.g., acknowledging receipt of data, pollingof APs, area-clearing operations, channel acquisition, carrier-sensingmaintenance functions, etc.). Management frames can be used for varioussupervisory functions (e.g., for joining and departing from wirelessnetworks, etc.).

Certain aspects of the present disclosure support allowing APs 104 toschedule STAs 106 transmissions in optimized ways to improve efficiency.Both high efficiency wireless (HEW) stations, stations utilizing an802.11 high efficiency protocol, and stations using older or legacy802.11 protocols, can compete for access to a wireless medium. Thehigh-efficiency 802.11 protocol described herein can allow for devicesto operate under a modified mechanism that differentiates betweendevices that can communicate concurrently and devices that cannotcommunicate concurrently. Accordingly, in the case of apartmentbuildings or densely-populated public spaces, APs and/or STAs that usethe high-efficiency 802.11 protocol can experience reduced latency andincreased network throughput even as the number of active wirelessdevices increases, thereby improving user experience.

In some embodiments, APs 104 can control access to a wireless medium bytransmitting a message using a transmission characteristic such that atleast the wireless devices to be silenced can decode the message and asecond group of wireless devices can access the medium fortransmissions. For example, with respect to FIG. 1, STAs 106 a and 106 bcan be legacy STAs and 106 c and 106 d can be HEW STAs. In thisembodiment, it can be desirable to silence the STAs 106 a and 106 b sothat the STAs 106 c and 106 d can communicate with the AP 104 withoutinterference from legacy STAs 106 a and 106 b. Thus, the transmissioncharacteristic can be such that at least the STAs 106 a and 106 b candecode the message. When the STAs 106 a and 106 b detect the message,the STAs 106 a and 106 b can be silenced for the interval as identifiedby the duration field within the message. The duration field of themessage can be set such that a predetermined percentage of a totalcommunication time is reserved for the STAs 106 c and 106 d tocommunicate. The STAs 106 c and 106 d can also be able to decode themessage but can receive an instruction to not set their networkallocation vector (NAV) and thus not be silenced for the intervalidentified in the duration field of the message.

In some aspects, an AP 104 or a STA 106 can transmit a message with atransmission characteristic that reserves the medium for only HEW STAsor a group of HEW STAs by sending a message that sets the NAV for thelegacy STAs but not for the HEW STAs. In other aspects, an AP 104 or aSTA 106 can transmit a message with a transmission characteristic thatreserves the medium for only legacy STAs or a group of legacy STAs bysending a message that sets the NAV of the HEW STAs but not the legacySTAs. This would allow the AP 104 to more efficiently allocate access tothe medium between the HEW STAs and the legacy STAs.

In one embodiment, the transmission characteristic can be a new frameformat with a new type and new subtype. In this implementation, withrespect to FIG. 1, the STAs 106 a and 106 b can be operating in a modeaccording to a legacy IEEE 802.11 standard (i.e. IEEE 802.11b) and STAs106 c and 106 d can be operating in a mode according to a IEEE 802.11high efficiency protocol. In one embodiment, the new frame can have asimilar structure as an 802.11b (or similar protocol) frame such thatlegacy STAs 106 a and 106 b can be able to decode the NAV for this newframe irrespective of the new type and subtype. The STAs 106 a and 106 bcan then set their NAV according to the new frame. The HEW STAs 106 cand 106 d, on the other hand, can decode the new frame but determinethat for this new frame type, as indicated by the type or subtype field,they can ignore the NAV for the new frame and thus can sendtransmissions during the time indicated by the duration field of the newframe. In some embodiments, the new frame format can be only decodableby one group of STAs (i.e. the new frame is not decodable by legacystations). In this implementation, with respect to FIG. 1, the STAs 106a and 106 b can be operating in a mode according to a legacy IEEE 802.11standard (i.e. IEEE 802.11b) and STAs 106 c and 106 d can be operatingin a mode according to a IEEE 802.11 high efficiency protocol. In thisembodiment, the new frame may only be decodable by STAs 106 c and 106 d.The STAs 106 c and 106 d can then set their NAV according to the newframe while the STAs 106 a and 106 b can be unable to decode the newframe and thus can send transmissions as if medium was idle. In someembodiments, the new frame can also indicate a group of HEW STAs thatcan set their NAV or a group of HEW stations that can ignore the NAV,which can reserve the medium for a certain group of HEW stations. Forexample, the new frame can include an indication that STA 106 c shouldset its NAV while STA 106 d can ignore the NAV and transmit freely. Insome aspects the new frame format can be similar to the format of arequest to send (RTS), clear to send (CTS) or a QoS null frame.

In some embodiments, the transmission characteristic can be informationin a field of an existing frame format. In one aspect, the AP 104 cantransmit a clear-to-send (CTS)-to-self frame. In one embodiment, the AP104 can set the receiver address (RA) of the CTS frame to a multicastaddress or to a specific medium access control (MAC) address to indicateto a first group of STAs to ignore the NAV of the CTS frame while asecond group of STAs can set their NAV according to the CTS frame. Forexample, with respect to FIG. 1, STAs 106 a and 106 b can be legacy STAsand 106 c and 106 d can be HEW STAs. The STAs 106 a and 106 b can settheir NAV according to the CTS, while the HEW STAs 106 c and 106 d, onthe other hand, can see the RA multicast address as an indication to notset their NAV and can thereby be able to transmit during the duration ofthe CTS. In another embodiment, the AP 104 can set the receiver address(RA) of the CTS frame to a multicast address or to a specific mediumaccess control (MAC) address and use one of the bits in the scramblingsequence in the service field of the CTS frame to indicate to a firstgroup of STAs to ignore the NAV of the CTS frame while a second set ofSTAs can set their NAV according to the CTS frame.

In another aspect, the AP 104 can transmit a request to send (RTS)frame. In one embodiment, the AP 104 can set the transmitter address(TA) to a multicast address and use one of the bits in the scramblingsequence in the service field of the RTS to indicate to a first group ofSTAs to ignore the NAV of the RTS frame while a second group of STAs canset their NAV according to the RTS frame. For example, with respect toFIG. 1, STAs 106 a and 106 b can be legacy STAs and 106 c and 106 d canbe HEW STAs. The STAs 106 a and 106 b can set their NAV according to theRTS, while the HEW STAs 106 c and 106 d, on the other hand, can see theTA multicast address and the use of the one bit in the service field asan indication to not set their NAV and can thereby be able to transmitduring the duration of the RTS. In other embodiments, the AP 104 cantransmit any data or management frame and set the TA to a multicastaddress and use one of the bits in the scrambling sequence in theservice field of the data or management frame to indicate to a firstgroup of STAs to ignore the NAV of the data or management frame while asecond group of STAs can set their NAV according to the data ormanagement frame.

In another aspect, an AP 104 or a STA 106 can transmit a quality ofservice (QoS) frame. In one embodiment, the AP 104 can use a one bitindication in the reserved bits of the QoS control field to indicate toa first group of STAs to ignore the NAV of the QoS frame while a secondgroup of STAs can set their NAV according to the QoS frame. For example,with respect to FIG. 1, STAs 106 a and 106 b can be legacy STAs and 106c and 106 d can be HEW STAs. The STAs 106 a and 106 b can set their NAVaccording to the QoS, while the HEW STAs 106 c and 106 d, on the otherhand, can see the one bit indication in the control field as anindication to not set their NAV and can thereby be able to transmitduring the duration of the QoS.

In another aspect, the AP 104 can transmit a control wrapper frame. Insome embodiments the control wrapper frame can carry an RTS or CTSframe. In one embodiment, the AP 104 can use an invalid field setting inthe high throughput control field of the control wrapper frame toindicate to a first group of STAs to ignore the NAV of the controlwrapper frame while a second group of STAs can set their NAV accordingto the control wrapper frame. For example, with respect to FIG. 1, STAs106 a and 106 b can be legacy STAs and 106 c and 106 d can be HEW STAs.The STAs 106 a and 106 b can set their NAV according to the controlwrapper frame (with a RTS, CTS, or other frame), while the HEW STAs 106c and 106 d, on the other hand, can see the invalid field settings inthe high throughput control field as an indication to not set their NAVand can thereby be able to transmit during the duration of the controlwrapper frame.

In one embodiment, the transmission characteristic can be information ina protocol version field. In this embodiment, the AP 104 can transmit aframe with a protocol version field set a value greater than zero thatcan be decodable by a first group of STAs to set the NAV according tothe frame while a second group of STAs may not be able to decode theframe and thus may not set their NAV. For example, with respect to FIG.1, STAs 106 a and 106 b can be legacy STAs and 106 c and 106 d can beHEW STAs. The STAs 106 a and 106 b may not be able to decode a framewith a protocol version field set to a value greater than zero, whilethe HEW STAs 106 c and 106 d, on the other hand, can be able to decodethis frame and can set their NAV according to the frame. Thus, the STAs106 a and 106 b can be able to transmit during the duration of theframe.

In another embodiment, the transmission characteristic can beinformation in a duration field. In this embodiment, the AP 104 cantransmit a frame with a duration field set to an invalid value that canbe decodable by a first group of STAs to set the NAV according to theframe while a second group of STAs may not be able to decode the frameand thus may not set their NAV. For example, with respect to FIG. 1,STAs 106 a and 106 b can be legacy STAs and 106 c and 106 d can be HEWSTAs. The STAs 106 a and 106 b may not be able to decode a frame with aduration field set to an invalid value, while the HEW STAs 106 c and 106d, on the other hand, can be able to decode this frame and can set theirNAV according to the frame. Thus, the STAs 106 a and 106 b can be ableto transmit during the duration of the frame.

In another embodiment, the transmission characteristic can beinformation in a field of an existing frame format. In one embodiment,the AP 104 can transmit a frame with a duration field set to zero. Theframe can include a new field, such that the new field can be decodableby a first group of STAs to set the NAV according to the new field ofthe frame while a second group of STAs may not be able to decode the newfield in the frame and thus may not set their NAV. For example, withrespect to FIG. 1, STAs 106 a and 106 b can be legacy STAs and 106 c and106 d can be HEW STAs. The STAs 106 a and 106 b may not be able todecode the new frame, while the HEW STAs 106 c and 106 d, on the otherhand, can be able to decode the new field in the frame and can set theirNAV according to the new field. Thus, the STAs 106 a and 106 b can beable to transmit during the duration of the frame.

In some aspects, an AP 104 or a STA 106 can subsequently transmit amessage with a transmission characteristic such that only HEW STAs or agroup of HEW STAs can reset the NAV while the legacy STAs do not resettheir NAV. In other aspects, an AP 104 can subsequently transmit amessage with a transmission characteristic such that only legacy STAs ora group of legacy STAs can reset their NAV while the HEW STAs do notreset their NAV. This would allow the AP 104 to more efficientlyallocate access to the medium between the HEW STAs and the legacy STAs.

In one embodiment, the transmission characteristic can be information ina CF-end frame. In this embodiment the AP 104 can transmit a CF-endframe and can set the basic service set identifier (BSSID) to amulticast address to indicate to a first group of STAs to ignore theCF-end frame while a second group of STAs can reset their NAV accordingto the CF-end frame. For example, with respect to FIG. 1, STAs 106 a and106 b can be legacy STAs and 106 c and 106 d can be HEW STAs. The STAs106 a and 106 b can reset their NAV according to the CF-end, while theHEW STAs 106 c and 106 d, on the other hand, can see the BSSID multicastaddress as an indication to not reset their NAV.

In another embodiment, the transmission characteristic can be a CF-endframe in a new frame format. In some embodiments, the new CF-end frameformat can be only decodable by one group of STAs. In thisimplementation, with respect to FIG. 1, the STAs 106 a and 106 b can beoperating in a mode according to a legacy IEEE 802.11 standard (i.e.IEEE 802.11b) and STAs 106 c and 106 d can be operating in a modeaccording to a IEEE 802.11 high efficiency protocol. In this embodiment,the new CF-end frame may only be decodable by STAs 106 c and 106 d. TheSTAs 106 c and 106 d can then reset their NAV according to the newCF-end frame while the STAs 106 a and 106 b can be unable to decode thenew frame and thus may not reset their NAV.

In one embodiment, the transmission characteristic can be a new frameformat with a new type and new subtype, such that the new frame formatis not decodable by legacy stations. In this implementation, withrespect to FIG. 1, the STAs 106 a and 106 b can be operating in a modeaccording to a legacy IEEE 802.11 standard (i.e. IEEE 802.11b) and STAs106 c and 106 d can be operating in a mode according to a IEEE 802.11high efficiency protocol. In one embodiment, the new frame can have asimilar structure as an 802.11b (or similar protocol) frame (i.e. aCF-end frame) but STAs 106 a and 106 b may not be able to decode the newframe and thus may not reset their NAV. The HEW STAs 106 c and 106 d, onthe other hand, can decode the new frame and determine that for this newframe type, they can reset the NAV and thus can access the medium.

In some embodiments, an AP 104 or a STA 106 can reserve the medium forvariable period of time. In one aspect, the AP 104 or the STA 106 cansend a message instructing the STAs to wait an indicated number of timeslots before attempting to access the medium. Each STA receiving themessage can perform a backoff procedure with a counter initialized atthe indicated time slot value. After each time slot, the STAs can checkto see if the medium was busy during the time slot. If the medium wasbusy, the counter can stay at the previous time slot value. If themedium was idle, the counter can decrease by one, and can continue towait until the counter reaches zero. Thus, the time period the AP 104 orthe STA 106 reserves the medium for can depend on the traffic in themedium and may not be a defined value.

Certain aspects of the present disclosure support allowing APs and STAsto selectively set the NAV of certain subsets of nodes using an RTS/CTSexchange in optimized ways to improve efficiency. Generally, wirelessnetworks that use a regular 802.11 protocol (e.g., 802.11a, 802.11b,802.11ac, 802.11g, 802.11n, etc.) operate under a carrier sense multipleaccess (CSMA) mechanism for medium access. According to CSMA, devicessense the medium and only transmit when the medium is sensed to be idle.The use of the CSMA mechanism can create inefficiencies because some APsor STAs located inside or outside of a base service area (BSA) can beable to transmit data without interfering with a transmission made by anAP or STA in the BSA. As the number of active wireless devices continuesto grow, the inefficiencies can begin to significantly affect networklatency and throughput. The RTS/CTS exchange protocol described hereincan allow for devices to operate under a modified mechanism thatdifferentiates between devices that can communicate concurrently withthe devices that are exchanging the RTS and CTS frames and devices thatcannot communicate concurrently. Accordingly, in the case of apartmentbuildings or densely-populated public spaces, APs and/or STAs that usethe modified RTS/CTS protocol discussed herein can experience reducedlatency and increased network throughput even as the number of activewireless devices increases, thereby improving user experience.

FIG. 3 is a diagram of an exemplary wireless communication system 300for a channel x. In the illustrated embodiment, the wirelesscommunication system 300 includes a plurality of APs (e.g., AP1 x, AP2x, AP3 x, and AP4), each having a BSA 301-304, and STAs (e.g., STA1 x,STA2 x, and STA4). In some embodiments the various operations of APs andSTAs described herein can be interchanged. For each AP-STA link (e.g.,reference link 315) working on channel x, the number of bytessuccessfully received can be expressed in the following way:

$f\begin{pmatrix}{{\sum\limits_{\underset{{CSMA}\mspace{14mu} {range}}{{ch}\mspace{14mu} x\mspace{14mu} i\; n}}{{Data}\mspace{14mu} {Tx}}} + {\sum\limits_{\underset{{CSMA}\mspace{14mu} {range}}{{ch}\mspace{14mu} x\mspace{14mu} {outside}}}{{Data}\mspace{14mu} {Tx}}} +} \\{{\sum\limits_{{ch}\mspace{14mu} x}{{ACK}\mspace{14mu} {Tx}}} + {\sum\limits_{{ch} \neq x}{{Data}\mspace{14mu} {Tx}}} + {\sum\limits_{{ch} \neq x}{{ACK}\mspace{14mu} {Tx}}}}\end{pmatrix}$

An RTS/CTS exchange can alter the total number of bytes received byeffectively the data transmissions (Tx) on the channel x outside theCSMA range and the acknowledgement (ACK) transmissions on channel x tozero. Nodes that send data transmissions (Tx) on the channel x outsidethe CSMA range and nodes that send acknowledgement (ACK) transmissionson channel x can be considered “jammers” that can cause interferencewith a given reference link 315 on channel x. Given that RTS/CTSmessages silence the nodes receiving the messages, usage of RTS/CTS candecrease system throughput. However, the RTS/CTS exchange can reduceinterference and improve reception for a given STA when there are manydevices present that can cause interference.

FIG. 4 is a diagram of an exemplary RTS/CTS exchange 400. In conjunctionwith FIG. 1, in some embodiments, an AP 104 can transmit a RTS frame toa STA 106 and the STA 106 can respond to the RTS frame by sending a CTSframe to the AP 104. An RTS/CTS exchange can be desirable for hiddennode mitigation or for clearing the medium when data transmission is notsuccessful for STAs 106. As shown in FIG. 4, the AP1 can transmit an RTS405 or other message to STA1 with the RTS 405 deferring all STAs and APswithin the defer range 401. AP2 is outside the defer range 401, and canbe considered a hidden node with respect to the AP1. As shown in FIG. 4,the AP2 can transmit a message 410 to STA2 with its own defer range 402which can interfere with STA1's reception of the RTS 405 or with itstransmission of a responsive CTS frame.

FIGS. 5 and 6 illustrate the effects of the RTS/CTS system. FIG. 5 is adiagram 500 of an exemplary RTS/CTS exchange. FIG. 6 is a time sequencediagram 600 of the RTS/CTS exchange of FIG. 5. In FIGS. 5 and 6, the AP1transmits to STA1 a RTS fame 601 with a defer range 501. STA1 thenresponds with a CTS frame 602 with a defer range 502. In conjunctionwith FIG. 3, the AP2 (hidden node) is then deferred and will remain forthe period 610 while the AP1 transmits a data packet 604 to the STA1 andthe STA sends an ACK or Block ACK 606. Thus, the RTS 601 and CTS 602 canreserve the medium and prevent interference from any hidden nodes (AP2)during a data transmission 604.

However, if the nodes generate RTS/CTS messages to mitigate the ACKinterference effect, the usage of RTS/CTS can be intrusive on thesystem. For example, N number of jammers can affect a STA (STA1 x asshown in FIG. 3). In one aspect, the throughput of the system wouldequal the sum of the throughputs for all the N jammers (Σ_(j=jammers)Thj=Thjammer). The throughput of the system with an RTS/CTS exchangewould equal the throughput of the non-silenced stations, STA1 x as shown(Σ_(j≦non silenced STA)Thj=Throughput of STA1 x≡Thsta). If the AP1 x orthe STA1 x are aware of a number M (N>M) such that of the number Njammers, M jammers should be silenced so that the STA1 x can transmitdata with a throughput Thsta*. In such a system, the system throughputwould equal the throughput of STA1 x plus the sum of the throughputs ofthe non-silenced jammers (e.g., Thsta*+Σ_(j=N−M non silenced jammers)Thj>Thjammer>Thsta). An AP 104 or a STA 106 can identify the number ofjammers by any conventional means. In some aspects, the AP 104 canperform a scan procedure to identify neighboring basic service sets(BSSs) and the related nodes. In some aspects, the AP 104 can then senda querying message (such as, for example, one or more beacon requestmessages) to the STA 106 that is the intended recipient of the data(e.g., STA1 is intended recipient of data 604 in FIG. 6). The BSSs heardby the AP 104 and not contained in the querying messages of the STAidentify the jammers that should not be silenced (N-M).

FIG. 7 is a diagram of an exemplary RTS/CTS exchange in a wirelesscommunication system 700. For example, as shown in FIG. 7, STA1 and AP1can use an RTS/CTS exchange to selectively silence certain jammerswithin their respective defer ranges 701 and 702. In this embodiment, itcan be desirable to silence the transmissions at AP2, AP3, AP4, and AP6and allow the transmission at AP5 so that AP5 can communicate with STA5while AP1 communicates without STA1 interference from jammer nodes.

In various embodiments, devices such as the AP1 can modulate a transmitpower of the RTS in order to decrease the number of exposed nodes andsources that generate ACK interference. For example, the AP1 cangradually increase transmit power of the RTS so as to silence AP6 butnot to silence AP5. Systems and methods for such transmit powermodulation are described in greater detail below with respect to FIGS. 8and 9.

FIG. 8 shows a flowchart 800 for an exemplary method of wirelesscommunication that can be employed within the wireless communicationsystem 100 of FIG. 1. The method can be implemented in whole or in partby the devices described herein, such as the wireless device 202 shownin FIG. 2. Although the illustrated method is described herein withreference to the wireless communication system 100 discussed above withrespect to FIG. 1, the wireless device 202 discussed above with respectto FIG. 2, and the wireless communication system 700 discussed abovewith respect to FIG. 7, a person having ordinary skill in the art willappreciate that the illustrated method can be implemented by anotherdevice described herein, or any other suitable device. Although theillustrated method is described herein with reference to a particularorder, in various embodiments, blocks herein can be performed in adifferent order, or omitted, and additional blocks can be added.

First, at block 810, the wireless device 202 determines an interferencelevel for a data transmission. For example, the AP1 can determine aninterference level for data transmission to the STA1. In variousembodiments, the interference level comprises a packet error rate (PER)from the AP1 to the STA1. Thus, in some embodiments, the AP1 candetermine PER of the data transmission to the STA1.

Next, at block 820, the wireless device 202 sets a transmission powerlevel, for a message reserving the wireless medium, based on theinterference level. For example, the AP1 can set a transmission powerlevel for RTS based on the interference level. As discussed in greaterdetail herein, in some embodiments, the AP1 can gradually increase theRTS transmission power level until the PER falls below a threshold errorrate or value.

Then, at block 830, the wireless device 202 transmits the messagereserving the wireless medium at the set transmission power level. Forexample, the AP1 can transmit the RTS at the set transmission powerlevel. In various embodiments, the message reserving the wireless mediumcan include one of a request-to-send (RTS) packet and a clear-to-send(CTS) packet.

In various embodiments, the wireless device can identify one or morepotentially interfering devices, order the potentially interferingdevices based on an estimated transmit power level to reach eachpotentially interfering device, and set the transmission power level forthe message reserving the wireless medium further based on the ordering.For example, the AP1 can identify the AP5 and the AP6 as potentiallyinterfering devices. The AP1 can order the RTS transmission power levelestimated to reach the AP5 and AP6, and the AP1 can set the RTStransmission power level to the lowest of the two values.

In various embodiments, setting the transmission power level of themessage reserving the wireless medium can include selecting a lowestestimated transmit power level in the ordering and selecting a nexthighest estimated transmit power level in the ordering when theinterference level satisfies a threshold value (for example, is greaterthan, or is less than, the threshold, depending on the particularinterference level or interference metricused). For example, the AP1 canestimate that the AP6 requires a first RTS transmission power level, andthe AP5 requires a second RTS transmission power level higher than thefirst. The AP1 can first transmit an RTS at the first transmission powerlevel and then measure the PER of data transmission to STA1. If the PERis greater than a threshold, the AP1 can next transmit an RTS at thesecond transmission power level, and so on.

In various embodiments, identifying the one or more potentiallyinterfering devices can include scanning for neighboring basic servicesets (BSSs), transmitting a querying message (such as, for example, abeacon request) to an intended recipient (e.g., receiving device) of thedata transmission, and identifying devices included in a neighboringBSS, but not visible to or detected by the intended recipient of thedata transmission, as potentially interfering devices. For example, theAP1 can scan for neighboring BSSs and can determine that AP5 and AP6 arein range. The AP1 can query the STA1 to determine that only AP2 and AP3are detected by the STA1. In some embodiments, devices visible to ordetected by STA1 comprise devices within the CTS defer range 702 (e.g.,AP2, STA2, AP3, STA4, STA6). In some embodiments, devices not visible ordetected by STA 1 comprise devices outside the CTS defer range 702(e.g., AP5, STA5, AP6). Thus, the AP1 can determine that the AP5 and theAP6 are potentially interfering devices which are detected by the AP1but not visible or detected by STA1 (e.g., within RTS defer range 701and outside CTS defer range 702).

In various embodiments, estimated transmit power level can be based on atransmit power control (TPC) information element (IE) included in abeacon. For example, the AP1 can receive beacons from the AP5 and theAP6. Each beacon can include an IE including TCP information indicativeof a transmit power level to reach each respective AP. In variousembodiments, other mechanisms for estimating or determining a transmitpower level can be used.

In various embodiments, potentially interfering devices can includedevices producing (or capable of producing, or likely to produce)acknowledgement (ACK) interference. For example, as shown in FIG. 7, theAP6 can be a potentially interfering device. In various embodimentsherein, transmission power level can be adjusted based on the entirety,or a subset, of actually or potentially interfering devices.

In an embodiment, the method shown in FIG. 8 can be implemented in awireless device that can include a determining circuit, a settingcircuit, and a transmitting circuit. Those skilled in the art willappreciate that a wireless device can have more components than thesimplified wireless device described herein. The wireless devicedescribed herein includes only those components useful for describingsome prominent features of implementations within the scope of theclaims.

The determining circuit can be configured to determine the interferencelevel. In an embodiment, the receiving circuit can be configured toimplement block 810 of the flowchart 800 (FIG. 8). The determiningcircuit can include one or more of the receiver 212 (FIG. 2), thetransceiver 214 (FIG. 2), the antenna 216 (FIG. 2), the DSP 220 (FIG.2), the processor 204 (FIG. 2), the signal detector 218 (FIG. 2), andthe memory 206 (FIG. 2). In some implementations, means for determiningcan include the determining circuit.

The setting circuit can be configured to set the transmission powerlevel for the message reserving the wireless medium. In an embodiment,the setting circuit can be configured to implement block 820 of theflowchart 800 (FIG. 8). The setting circuit can include one or more ofthe transmitter 210 (FIG. 2), the transceiver 214 (FIG. 2), theprocessor 206 (FIG. 2), the DSP 220 (FIG. 2), and the memory 204 (FIG.2). In some implementations, means for setting can include the settingcircuit.

The transmitting circuit can be configured to transmit the messagereserving the wireless medium. In an embodiment, the transmittingcircuit can be configured to implement block 830 of the flowchart 800(FIG. 8). The transmitting circuit can include one or more of thetransmitter 210 (FIG. 2), the transceiver 214 (FIG. 2), and the antenna216 (FIG. 2). In some implementations, means for transmitting caninclude the transmitting circuit.

FIG. 9 shows a flowchart 900 for an exemplary method of wirelesscommunication that can be employed within the wireless communicationsystem 100 of FIG. 1. The method can be implemented in whole or in partby the devices described herein, such as the wireless device 202 shownin FIG. 2. Although the illustrated method is described herein withreference to the wireless communication system 100 discussed above withrespect to FIG. 1, the wireless device 202 discussed above with respectto FIG. 2, and the wireless communication system 700 discussed abovewith respect to FIG. 7, a person having ordinary skill in the art willappreciate that the illustrated method can be implemented by anotherdevice described herein, or any other suitable device. Although theillustrated method is described herein with reference to a particularorder, in various embodiments, blocks herein can be performed in adifferent order, or omitted, and additional blocks can be added.

First, at block 910, the wireless device 202 scans for neighboring basicservice sets. For example, the AP1 can scan for neighboring basicservice sets by listening for beacons from wireless devices within theneighboring basic service sets. The AP1 can receive beacons from the AP5and the AP6. In some embodiments, the beacons can include IEs indicatingTCP information. Thus, the AP1 can estimate a transmission power levelto reach each of the AP5 and the AP6.

Next, at block 920, the wireless device 202 transmits a querying messageto an intended recipient of data transmission. For example, the AP1 cantransmit a beacon request to the STA1. The STA1 can receive beacons fromthe AP1, the AP2, and the AP3. Thus, the STA1 can identify one or moreof the AP1, the AP2, and the AP3 to the AP1. The wireless device 202 canreceive a query response from the intended data recipient. The queryresponse may include a list of devices from which it has receivedbeacons from (e.g., detected devices).

Then, at block 930, the wireless device 202 identifies one or moredevices included in a neighboring BSS, but not visible to the intendeddata recipient. For example, the AP1 can subtract the set of APs visibleto or detected by the STA1 from the set of APs visible to or detected bythe AP1. Thus, the AP1 can identify the AP5 and the AP6 as potentialjammers (e.g., devices within RTS defer range 701 and outside CTS deferrange 702).

Subsequently, at block 940, the wireless device 202 orders theidentified devices based on an estimated transmit power level to reacheach device. For example, the AP1 can determine transmit power levels toreach each of AP5 and AP6 (for example, based on their beacons asdiscussed above). AP6 can be associated with a first transmit powerlevel and the AP5 can be associated with a second transmit power level,higher than the first level. Thus, the transmit power level of AP6 canbe placed first in a vector and the transmit power level of AP5 can beplaced second in the vector. Additional APs not shown can be similarlyordered.

Thereafter, at block 950, the wireless device 202 sets the transmissionpower level for an RTS to the lowest estimated transmit power level. Forexample, the AP1 can set RTS transmission power level to the firsttransmit power level associated with the AP6.

Next, at block 960, the wireless device 202 performs RTS/CTS and/or datatransmission. For example, the AP1 can transmit the RTS at the firsttransmit power level, the STA1 can transmit the CTS, and the AP1 cantransmit data to the STA1 as discussed above with respect to FIG. 6.

Then, at block 970, the wireless device 202 can measure the PER of thedata transmission. For example, the AP1 can measure the PER of the datatransmission to the STA1, and can compare the measured PER to athreshold value. In various embodiments, the threshold can be preset ordynamically determined. If the PER is less than or equal to thethreshold, the wireless device 202 can proceed to maintain the currentlyset RTS transmission power level at block 980.

Alternatively, if the PER is greater than the threshold, the wirelessdevice 202 can proceed to block 990. At block 990, the wireless device202 sets RTS transmission power level to the next highest estimatedtransmit power in the ordered vector. For example, the AP1 can set theRTS transmit power level to the second transmit power associated withthe AP5. Where the wireless system includes additional APs not shown,blocks 960-990 can be repeated in a similar manner for each newtransmission power level. Accordingly, the wireless device 202 canmodulate RTS transmission power level to increase likelihood ofexcluding ACK interference (e.g., AP6) while decreasing the likelihoodof silencing exposed terminals (e.g., AP5).

A person/one having ordinary skill in the art would understand thatinformation and signals can be represented using any of a variety ofdifferent technologies and techniques. For example, data, instructions,commands, information, signals, bits, symbols, and chips that can bereferenced throughout the above description can be represented byvoltages, currents, electromagnetic waves, magnetic fields or particles,optical fields or particles, or any combination thereof.

Various modifications to the implementations described in thisdisclosure can be readily apparent to those skilled in the art, and thegeneric principles defined herein can be applied to otherimplementations without departing from the spirit or scope of thisdisclosure. Thus, the disclosure is not intended to be limited to theimplementations shown herein, but is to be accorded the widest scopeconsistent with the claims, the principles and the novel featuresdisclosed herein. The word “exemplary” is used exclusively herein tomean “serving as an example, instance, or illustration.” Anyimplementation described herein as “exemplary” is not necessarily to beconstrued as preferred or advantageous over other implementations.

Certain features that are described in this specification in the contextof separate implementations also can be implemented in combination in asingle implementation. Conversely, various features that are describedin the context of a single implementation also can be implemented inmultiple implementations separately or in any suitable sub-combination.Moreover, although features can be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination can be directed to asub-combination or variation of a sub-combination.

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover: a, b, c,a-b, a-c, b-c, and a-b-c.

The various operations of methods described above can be performed byany suitable means capable of performing the operations, such as varioushardware and/or software component(s), circuits, and/or module(s).Generally, any operations illustrated in the Figures can be performed bycorresponding functional means capable of performing the operations.

The various illustrative logical blocks, modules and circuits describedin connection with the present disclosure can be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array signal (FPGA) or other programmable logic device(PLD), discrete gate or transistor logic, discrete hardware componentsor any combination thereof designed to perform the functions describedherein. A general purpose processor can be a microprocessor, but in thealternative, the processor can be any commercially available processor,controller, microcontroller or state machine. A processor can also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

In one or more aspects, the functions described can be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions can be stored on or transmitted over as oneor more instructions or code on a computer-readable medium.Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage media can be anyavailable media that can be accessed by a computer. By way of example,and not limitation, such computer-readable media can comprise RAM, ROM,EEPROM, CD-ROM or other optical disk storage, magnetic disk storage orother magnetic storage devices, or any other medium that can be used tocarry or store desired program code in the form of instructions or datastructures and that can be accessed by a computer. Also, any connectionis properly termed a computer-readable medium. For example, if thesoftware is transmitted from a web site, server, or other remote sourceusing a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave, then the coaxial cable, fiber optic cable, twisted pair,DSL, or wireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and Blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Thus, in some aspects computer readable medium can comprisenon-transitory computer readable medium (e.g., tangible media). Inaddition, in some aspects computer readable medium can comprisetransitory computer readable medium (e.g., a signal). Combinations ofthe above should also be included within the scope of computer-readablemedia.

The methods disclosed herein comprise one or more steps or actions forachieving the described method. The method steps and/or actions can beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions can bemodified without departing from the scope of the claims.

Further, it should be appreciated that modules and/or other appropriatemeans for performing the methods and techniques described herein can bedownloaded and/or otherwise obtained by a user terminal and/or basestation as applicable. For example, such a device can be coupled to aserver to facilitate the transfer of means for performing the methodsdescribed herein. Alternatively, various methods described herein can beprovided via storage means (e.g., RAM, ROM, a physical storage mediumsuch as a compact disc (CD) or floppy disk, etc.), such that a userterminal and/or base station can obtain the various methods uponcoupling or providing the storage means to the device. Moreover, anyother suitable technique for providing the methods and techniquesdescribed herein to a device can be utilized.

While the foregoing is directed to aspects of the present disclosure,other and further aspects of the disclosure can be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

What is claimed is:
 1. A method of wireless communication over awireless communication medium comprising: determining a level ofinterference for a data transmission from a transmitting device to anintended receiving device; setting a transmission power level fortransmitting a message based on the interference level, the messagecomprising one of a request-to-send (RTS) packet and a clear-to-send(CTS) packet; and transmitting the message at the set transmission powerlevel.
 2. The method of claim 1, wherein the transmitting device and thereceiving device each comprises one of an access point and a station. 3.The method of claim 1, wherein the level of interference is based on atleast a packet error rate (PER) of the data transmission from thetransmitting device to the intended receiving device.
 4. The method ofclaim 1, further comprising: identifying one or more potentiallyinterfering devices detected by the transmitting device; ordering thepotentially interfering devices based on an estimated transmit powerlevel from the transmitting device to reach each of the potentiallyinterfering devices, wherein the ordering identifies from a lowestestimated transmit power to a highest estimated transmit power level;and setting the transmission power level for transmitting the messagebased further on the ordering of the estimated transmit power levels forthe potentially interfering devices.
 5. The method of claim 4, whereinthe setting of the transmission power level of the message comprises:selecting a smallest estimated power level from the lowest to thehighest estimated power levels in the ordering such that a newinterference level based on the data transmission at the selectedsmallest transmit power level satisfies a threshold value.
 6. The methodof claim 4, wherein the setting of the transmission power level of themessage comprises: selecting a smallest estimated power level from thelowest to the highest estimated power levels in the ordering for a firsttransmission of the message from the transmitting device to thereceiving device; transmitting the first transmission at the selectedsmallest transmit power level; determining an interference level for thefirst transmission; selecting a next highest estimated power level fromthe lowest to the highest estimated power levels for a secondtransmission of the message if the interference level for the firsttransmission is greater than the threshold; transmitting the secondtransmission at the selected next highest estimated transmit powerlevel; determining an interference level for the second transmission;selecting a next highest estimated power level from the lowest to thehighest estimated power levels for a third transmission of the messageif the interference level of the second transmission is greater than thethreshold; and setting the transmission power level of the message toselected estimated power level if an interference level of one of thedata transmissions is less than the threshold.
 7. The method of claim 4,wherein identifying the one or more potentially interfering devicescomprises: scanning for neighboring basic service sets (BSSs);transmitting a querying message from the transmitting device to theintended receiving device of the data transmission; and identifyingdevices included in a neighboring BSS from the scanned list ofneighboring BSSs, but not detected by the intended receiving device ofthe data transmission, as potentially interfering devices.
 8. The methodof claim 6, wherein scanning for neighboring BSSs comprises receivingbeacons from potentially interfering devices, wherein the estimatedtransmit power level is based on a transmit power control (TPC)information element (IE) included in the received beacons.
 9. The methodof claim 6, further comprising receiving a query response message fromthe intended receiving device identifying a list of devices detected bythe intended receiving device as potentially interfering devices for thedata transmission from the transmitting device to the intended receivingdevice.
 10. The method of claim 8, wherein identifying devices includedin a neighboring BSS from the scanned list of neighboring BSSs, but notdetected by the intended receiving device of the data transmission, aspotentially interfering devices comprises comparing the potentiallyinterfering devices detected by the transmitting device with thepotentially interfering devices detected by the intended receivingdevice.
 11. The method of claim 4, wherein the estimated transmit powerlevel is based on a transmit power control (TPC) information element(IE) included in a beacon received from potentially interfering devices.12. The method of claim 4, wherein identifying potentially interferingdevices detected by the transmitting device comprises identifyingdevices transmitting acknowledgement (ACK) messages that may potentiallyinterfere with the data transmission from the transmitting device to theintended receiving device.
 13. An apparatus configured to performwireless communication over a wireless communication medium comprising:a processor configured to: determine a level of interference for a datatransmission to an intended receiving device; and set a transmissionpower level for transmitting a message based on the interference level,the message comprising one of a request-to-send (RTS) packet and aclear-to-send (CTS) packet; and a transmitter configured to transmit themessage at the set transmission power level.
 14. The apparatus of claim13, wherein the wherein the receiving device comprises one of an accesspoint and a station.
 15. The apparatus of claim 13, wherein the level ofinterference is based on at least a packet error rate (PER) of the datatransmission to the intended receiving device.
 16. The apparatus ofclaim 13, wherein the processor is further configured to: identify oneor more potentially interfering devices detected by the processor; orderthe potentially interfering devices based on an estimated transmit powerlevel from the transmitting device to reach each of the potentiallyinterfering devices, wherein the ordering identifies from a lowestestimated transmit power to a highest estimated transmit power level;and set the transmission power level for transmitting the message basedfurther on the ordering of the estimated transmit power levels for thepotentially interfering devices.
 17. The apparatus of claim 16, whereinthe processor is further configured to select a smallest estimated powerlevel from the lowest to the highest estimated power levels in theordering such that a new interference level based on the datatransmission at the selected smallest transmit power level satisfies athreshold value.
 18. The apparatus of claim 16, further comprising areceiver configured to scan for neighboring basic service sets (BSSs),wherein: the transmitter is further configured to transmit a queryingmessage to the intended receiving device of the data transmission; andthe processor is further configured to identify devices included in aneighboring BSS from the scanned list of neighboring BSSs, but notdetected by the intended receiving device of the data transmission, aspotentially interfering devices.
 19. The apparatus of claim 16, furthercomprising a receiver configured to receive beacons from the potentiallyinterfering devices, wherein the estimated transmit power level is basedon a transmit power control (TPC) information element (IE) included inthe beacons.
 20. The apparatus of claim 16, wherein the processor isfurther configured to identify devices producing acknowledgement (ACK)interference.
 21. An apparatus for wireless communication over awireless communication medium comprising: means for determining a levelof interference for a data transmission to an intended receiving device;means for setting a transmission power level for transmitting a messagebased on the interference level, the message comprising one of arequest-to-send (RTS) packet and a clear-to-send (CTS) packet; and meansfor transmitting the message at the set transmission power level. 22.The apparatus of claim 21, wherein the level of interference is based onat least a packet error rate (PER) of the data transmission from thetransmitting device to the intended receiving device.
 23. The apparatusof claim 21, further comprising: means for identifying one or morepotentially interfering devices; means for ordering the potentiallyinterfering devices based on an estimated transmit power level from thetransmitting means to reach each of the potentially interfering devices,wherein the ordering means identifies from a lowest estimated transmitpower to a highest estimated transmit power level; and means for settingthe transmission power level for transmitting the message based furtheron the ordering of the estimated transmit power levels for thepotentially interfering devices.
 24. The apparatus of claim 23, whereinmeans for setting the transmission power of the message reserving thewireless medium comprises means for selecting a smallest estimated powerlevel from the lowest to the highest estimated power levels in theordering such that a new interference level based on the selectedsmallest transmit power level satisfies a threshold value.
 25. Theapparatus of claim 23, wherein means for identifying the one or morepotentially interfering devices comprises: means for scanning forneighboring basic service sets (BSSs); transmitting a querying messageto the intended receiving device of the data transmission; and means foridentifying devices included in a neighboring BSS from the scanned listof neighboring BSSs, but not detected by the intended receiving deviceof the data transmission, as potentially interfering devices.
 26. Theapparatus of claim 23, wherein means for identifying potentiallyinterfering devices comprises identifying devices producingacknowledgement (ACK) interference.
 27. A non-transitorycomputer-readable medium comprising code that, when executed, causes anapparatus to: determine a level of interference for a data transmissionfrom a transmitting device to an intended receiving device; set atransmission power level for transmitting a message based on theinterference level, the message comprising one of a request-to-send(RTS) packet and a clear-to-send (CTS) packet; and transmit the messagethe message at the set transmission power level.
 28. The medium of claim27, further comprising code that, when executed, causes the apparatusto: identify one or more potentially interfering devices; order thepotentially interfering devices based on an estimated transmit powerlevel from the transmitting device to reach each of the potentiallyinterfering devices, wherein the ordering identifies from a lowestestimated transmit power to a highest estimated transmit power level;and set the transmission power level for transmitting the message basedfurther on the ordering of the estimated transmit power levels for thepotentially interfering devices.
 29. The medium of claim 28, whereinsetting the transmission power of the message reserving the wirelessmedium comprises: selecting a smallest estimated power level from thelowest to the highest estimated power levels in the ordering such that anew interference level based on the selected smallest transmit powerlevel satisfies a threshold value.
 30. The medium of claim 28, whereinidentifying the one or more potentially interfering devices comprises:scanning for neighboring basic service sets (BSSs); transmitting aquerying message from the transmitting device to the intended receivingdevice of the data transmission; and identifying devices included in aneighboring BSS from the scanned list of neighboring BSSs, but notdetected by the intended receiving device of the data transmission, aspotentially interfering devices.